A driver intends to economically drive a vehicle by considering fuel consumption (mileage) of the vehicle. Therefore, for example, at each time of supplying fuel to the vehicle, the mileage is calculated by using a driven distance and consumed fuel by resetting a trip meter of the vehicle. In order to easily calculate the mileage, a technology has been proposed in which the mileage is automatically displayed when the trip meter is reset (for example, see Patent Document 1).
However, by only automatically calculating the mileage, the driver cannot understand what drive operations cause to increase the mileage, and the automatic calculation of the mileage cannot be said to be sufficient to learn drive operations for increasing the mileage.
In addition, a technology has been proposed (for example, see Patent Document 2). In the technology, by comparing a mileage standard value of another vehicle with a mileage standard value of a user's own vehicle, when the mileage of the user's own vehicle has been decreased, the mileage decrease is displayed, and when drive operations for decreasing the mileage such as sudden acceleration and long idling time are detected, a warning is displayed. When the driver obtains the warning on the display, the driver understands what operations have decreased the mileage and can utilize the operations to increase the mileage afterward.
However, by only displaying the operations that cause to decrease the mileage, the driver does not sufficiently obtain what operations can increase the mileage. Consequently, it is insufficient to enable the driver to actively increase the mileage. In addition, it is well known that the sudden acceleration and the long idling time cause to decrease the mileage, and it is difficult for the driver to increase the mileage by only displaying such operations.    [Patent document 1] Japanese Patent Application Publication No. 2004-210086    [Patent document 2] Japanese Patent Application Publication No. 2001-108503